Ribbon feed and reversing mechanism for typewriters

ABSTRACT

A typewriter is provided with ribbon feed and reversing mechanism whereby when one ribbon spool becomes empty and the other correspondingly becomes full, the resistance to rotation of one or other spool causes the drive to be reversed so that as typing proceeds the ribbon is progressively wound back from the full spool to the empty one. There is a driving spindle which is rotated to and fro as the carriage makes its alternative typing and return traverses and racks one or other of two spool spindles through pawl and ratchet mechanisms. The driving spindle carries a cam which rotates inside an oscillatable member, and if the latter is prevented from rotating, oscillates the latter to operate the pawl and ratchet mechanisms. Upon one of these mechanisms encountering undue resistance to operation due to resistance of its spool to rotation, the oscillatable member is stepped round by the cam from one alternative position to another. The eccentric member carries an eccentric device which operates within a female member to displace the latter. Each pawl and ratchet mechanism is provided with a bluffing device, and according to the displaced position of the female member one or other of these devices is rendered operative to bluff its associated pawl and ratchet mechanism (thereby discontinuing the drive to the associated spool spindle) and the other of these bluffing devices is rendered inoperative to bluff the associated pawl and ratchet mechanism and the drive is thereby transferred to the other spool spindle.

United States Patent Edward Victor Byers l7 Cavendish Crescent, ThePark, England [21] Appl. No. 886,262

[72] Inventor [22] Filed Dec. 18, 1969 [45] Patented Dec. 28, 1971 [32]Priority Dec. 20, 1968 [33] Great Britain [31 60,540/68 [54] RIBBON FEEDAND REVERSING MECHANISM Primary Examiner-Robert E. Pulfrey AssistantExaminerStephen C. Pellegrino All0rneyPaul & Paul ABSTRACT: A typewriteris provided with ribbon feed and reversing mechanism whereby when oneribbon spool becomes empty and the other correspondingly becomes full,the resistance to rotation of one or other spool causes the drive to bereversed so that as typing proceeds the ribbon is progressively woundback from the full spool to the empty one. There is a driving spindlewhich is rotated to and fro as the carriage makes its alternative typingand return traverses and racks one or other of two spool spindlesthrough pawl and ratchet mechanisms. The driving spindle carries a camwhich rotates inside an oscillatable member, and if the latter isprevented from rotating, oscillates the latter to operate the pawl andratchet mechanisms. Upon one of these mechanisms encountering undueresistance to operation due to resistance of its spool to rotation, theosciilatable member is stepped round by the cam from one alternativeposition to another. The eccentric member carries an eccentric devicewhich operates within a female member to displace the latter. Each pawland ratchet mechanism is provided with a bluffing device, and accordingto the displaced position of the female member one or other of thesedevices is rendered operative to bluff its associated pawl and ratchetmechanism (thereby discontinuing the drive to the associated spoolspindle) and the other of these bluffing devices is rendered inoperativeto bluff the associated pawl and ratchet mechanism and the drive isthereby transferred to the other spool spindle.

PATENTEU ntcza I971 SHEET 2 BF 3 Dn O T N E V N I EDWARD VICTOR BYERZ?165.

BY MW:

ATTORNEYS.

PATENTED DEB28 I97! SHEET 3 UP 3 m T N E V N I EDWARD VlCTOR BYERS BY WATTORNEYS- RIBBON FEED AND REVERSING MECHANISM FOR TYPEWRITERS CROSSREFERENCE TO RELATED APPLICATIONS Reference is made to Brit. Pat.application No. 60,540/68 of 24th Dec. 1968, Edward Victor Byers, fromwhich priority is claimed.

SUMMARY OF THE INVENTION The invention concerns typewriters of the typehaving a traversing carriage, and two rotatable mountings for two ribbonspools between which spools the ribbon is fed as the carriage traverses,the mountings being driven alternatively in opposite directions so thatthe ribbon is first wound onto one spool and drawn off the other and issubsequently wound-back onto the other spool and drawn off the firstspool, whereby each spool is alternately wound and subsequently emptied.The invention is concerned with an improved mechanism for securing theautomatic reversal of the ribbon feed when either spool becomes empty.

The invention therefore provides ribbon feed and reversing mechanism fora typewriter of the type specified, comprising a driver which isrotatable as the carriage traverses, alternative driving means driven bythe driver for driving one mounting in one direction and the other inthe reverse direction, and reversing means for automatically changingover from one driving means to the other upon predetermined resistanceof a mounting to rotation and for thereby effecting the reversal of theribbon feed.

Specifically, there may be a rotatable driving cam, a deviceoscillatable by the rotating driving cam and normally held in any one ofalternative rotational positions by a detent unless prevented from beingoscillated whereupon said device is moved by the cam from one to anotherof the rotational positions, pawl and ratchet mechanisms operable bysaid device to drive the spool mountings in opposite directions and eachoperable, on encounting predetermined resistance of the associatedmounting to rotation, to prevent said device from being oscillated, abluffing device for each pawl and ratchet mechanism each bluffing devicebeing movable between a bluffing position in which the associated pawland ratchet mechanism is inoperative and an inoperative position inwhich said associated pawl and ratchet mechanism is operative, and meanswhereby the rotational position of the oscillatable device determineswhich of the bluffing devices is operative.

According to an important subsidiary feature of the invention, the lastsaid means comprises a bluff-operating eccentric device rotationallymovable with the oscillatable device between alternative positions forthe alternative bluffing of the pawl and ratchet mechanisms, a femalemember encircling the eccentric device and displaceable thereby toalternative positions, and bluffing connections extending from thefemale member to the pawl and ratchet mechanisms whereby one or theother of the latter is bluffed according to the position of the femalemember.

In order that the invention may be better understood, reference will nowbe made to the drawings accompanying the Provisional Specification inwhich:

FIG. I is a sectional elevation of the ribbon feed and reversingmechanism;

FIG. 2 is an inverted plan view of a portion thereof, partly in section;

FIG. 3 is an inverted plan of a further portion of the mechanism;

FIG. 4 is an end elevation of the pawl and ratchet mechanism for drivinga representative one of the two ribbon mountings, while FIG. 5 is anexploded view showing the main components of the feed and reversingmechanism.

In the accompanying drawings, those parts of the typewriter of the typespecified, which are not essential to an understanding of the invention(e.g. the keyboard, platen, carriage and associated mechanisms) are notillustrated, such parts being of a conventional and generally understoodcharacter.

The ribbon feed and reversing mechanism comprises a driving spindle 10which (being coupled to the carriage by any suitable mechanism, notshown) rotates first in one direction then the other as the carriagemakes its alternate typing and return traverses, and two spool spindlesll, 12 each driven thereby through pawl and ratchet mechanism The threespindles are appropriately journaled in the frame or chassis 13 of thetypewriter and the included angle between the lines joining the axis ofspindle I0 with the axes of spindles II and I2 is or nearly so. Theupper ends of the two spindles II, 12 constitute mountings for theremovable reception of two typewriter spools 14, I5 between which theribbon I6 extends. The function of the mechanism provided by thisinvention is to wind the ribbon offa full spool (such for example as I4)onto an empty spool (such for example as 15) and, when the initiallyfull spool 14 becomes empty and the initially empty spool 15 becomesfull, to reverse the direction of the ribbon feed so that the ribbon isthen wound back onto the spool 14 from spool 15.

At their lower ends the spindles ll, 12 carry ratchet wheels l7, 18respectively, having oppositely arranged teeth so that the spindles canbe racked round in opposite directions. At its lower end the spindle 10carries a driving cam 19 having a plurality of circumferentially spacedcrests or lobes to produce a plurality of complete oscillations of theoscillating device, hereinafter described, in each revolution. In theillustrated construction cam 19 is substantially triangular and operatesin a substantially square track recess 20 within a track. wall 21 formedon the upper surface of a disc 22. This track wall 21 is located withinholes 23a, 24a in annular portions 23, 24 formed on the ends ofpawl-carrying bars 25, 26. Hole 23a in bar 25 is substantially circularand track wall 21 is a rotational fit in it. Hole 24a in bar 26 iselongated in the direction of the length of that bar. The other end ofbar 25 has a pair of oppositely directed pawls 27 for racking theratchet wheel 17 in one direction, and two recesses 28. Similarly theopposite end of bar 26 has two oppositely directed pawls 29 for rackingthe rack wheel I8 in the opposite direction, and two recesses 30. Thefirst said end of bar 25 has a slot 30 in which a pin 31 on the firstsaid end of bar 26 is engaged, the two bars being coupled together by atension spring 32. This spring holds s detent nose 33 projecting inwardsfrom the periphery of the hole 23a in bar 25 into engagement with anyone of four detent notches 34 provided one in each of the four outerfaces of the wall 22. It will thus be appreciated that the disc 22(which, with its track wall 21 and parts 43, 44, 45 hereinaftermentioned, constitute the aforesaid oscillatable device) has fouralternative rotational positions but is normally prevented fromrotation, while feed is taking place, by detent nose 33 engaging in oneof the notches 34.

As a result, for each complete rotation of the triangular cam 19 thedisc 22 is caused to make three complete oscillations which oscillatethe bars 25, 26 and so cause either spindle II or spindle 12 to beracked round by one or other of the pawl and ratchet mechanismsconsisting of pawls 27 on the bar 25 and the teeth of ratchet wheel 17and pawls 29 on bar 26 and the teeth of ratchet wheel 18. One or otherof these pawl and ratchet mechanisms is bluffed or rendered inoperativewhile the other is rendered operative by bluffing mechanisms now to bedescribed.

Below the pawl bars 25, 26 there are the respective bluff bars 35, 36which are pivotally connected to one another at 37 at one end. Near itsfree end bluff bar 35 carries two upstanding pins 37 adapted to engagethe recesses 28 in the underside of pawl bar 25, while near its free endthe bluff bar 36 carries upstanding projections 38 adapted to engage therecesses 30 in the underside of pawl bar 26. The arrangement is suchthat if either bluff bar 35 or 36 is retracted towards the axis of shaft10 the other one is projected. The projections 37 and 38 of theretracted bar 35 or 36 engage the recesses 28 or 30 of the pawl bar 25or 26 and thus permit the pawls of that bar to engage the teeth ofratchet wheel 17 or 18 as the case may be. The

projections 38 or 37 of the projected bluffing bar 36 or 35 aredisengaged from these recesses and therefore hold the associated pawlbar 26 or 25 in an upper position in which its pawls'cannot engage theassociated ratchet wheel. Springs 41 acting on discs 42 urge the pawlbars 25, 26 downwards.

One bluffing bar is projected and the other retracted when either spool14, 15 ceases to rotate, by the following mechanism. At the underside ofdisc 22 there is an annular wall 43 having projecting from it a longradial lug 44 and two shorter lugs 45 at 90 to lug 44. These lugs andannular wall in effect constitute an eccentric device; they are locatedin a hole 46 through a female member 47 on the end of bar 36. Theperiphery of hole 46 has four inwardly protruding lands 48 at 90 to eachother. One of these lands is engaged by the long lug 44 and two othersare engaged by the shorter lugs 45 while the remaining land is engagedby the periphery of wall 43. Thus according to whichever of the fourlands 48 is engaged by the long lug 44 (that is to say, according to therotational position of the disc 22 and the eccentric device) one orother of the bars 35, 36 will be held projected and the other retracted.In FIG. 3 the bar 36 is held projected, and bar 35 is retracted, andthis results in spindle 11 being racked round the spindle 12 remainingstationary.

When either of the spool spindles 11, 12 is held against rotation, theassociated pawl bar 25 or 26 is prevented from oscillating and this inturn prevents the disc 22 from being oscillated by the rotating cam 19.Rotation of the cam 19 therefore causes the disc 22 to rotate so thatone of the notches 34 which has hitherto been engaged by the nose 33 isdisengaged therefrom and the next notch 34 is brought to a position inwhich it is engaged with the nose. Thus the disc 22 and the parts 43 to45 thereon make a movement through 90 between alternative positions andthis causes the long lug 44 at the underside of disc 22 to remove itselffrom one land 48 on bar 36 (with which land it has hitherto been engagedto hold bluff bar 35 or 36 projected) and to move rotationally intoengagement with the next land 48. Thereby the female member 47 isdisplaced and the first mentioned bluff bar is retracted and the otherbluff bar is projected, with the result that the drive is transferredfrom one of the spindles 11, 12 to the other spindle so that the ribbonis wound alternatively onto spool 14 from ribbon l and subsequently ontospool from ribbon 14.

The resistance to rotation of the spools, resulting in the changeover,occurs because one end of the ribbon 16 is anchored to spool 14 and theother end to spool 15. Thus when one spool becomes empty the pull of theribbon prevents that empty spool and its spindle, from being rotated andsimultaneously the fact that the end of the ribbon is anchored to theempty spool prevents the full spool, and its spindle, from beingrotated.

Cam 19 is formed on the underface of a member 50 keyed to spindle l0 andpositioned against a shoulder on the latter. The inner ends of bars 25,26, 35, 36 and the disc 22, are position between member 50 and a disc 51which is a push fit on the end of the spindle. This disc has acylindrical boss 52 extending through disc 22 into engagement with theunder face of cam 19.

The various parts 17, 18, 19, 22, 25,26, 35, 36, 42, 50 and 51 may bemoulded from a suitable plastic" material.

It is within the'scope of the invention to drive spindle 10 through aone-way coupling, or free wheel device, so that the spindle is onlyrotated as the carriage makes its typing traverses and is not rotatedduring the reverse traverses.

What is claimed is:

1. A ribbon feed and reversing mechanism for a traversing carriagetypewriter, comprising:

a. two ribbon spools for carrying a ribbon, each spool being carried bya rotatable mounting;

b. driving means coupled to and driven from said carriage,

and having a driving cam;

c. a pawl and ratchet mechanism connected to each said spool mounting,for driving said spools; d. an oscillatable device, for operating saidpawl and ratchet mechanisms, connected to said pawl and ratchetmechanisms through two respective pawl bars, said device driven by saiddriving cam;

. said device being rotatable into alternative rotational positions,such that said driving cam oscillates said device when in any one of itsalternative positions;

f. detent means engaging said device for normally holding said device inany one said alternative position while said device is being oscillated,said detent means being yieldable when said device is prevented frombeing oscillated to permit said device to rotate from one alternativeposition to another; and

g. bluffing means connected to and driven by said device for holdingsaid pawl and ratchet mechanisms in alternate nonoperative and operativepositions respectively, such that upon either spool encountering apredetermined resistance to rotation, said device is rotated to a nextof said alternative positions, the ribbon feed reversing as said deviceis rotated to each such position.

2. The apparatus as described in claim 1, wherein said bluffing meanscomprises a bluff-operating eccentric device rotationally movable withthe oscillatable device between alternative positions for thealternative bluffing of the pawl and ratchet mechanisms; a female memberencircling said eccentric device and displaceable thereby to alternativepositions, and bluffing connections extending from said female member toeach pawl and ratchet mechanism, whereby one of said mechanisms isnonoperative and the other operative according to the position of thefemale member.

3. The apparatus as described in claim 2, wherein said bluffingconnection extending from said female member to each pawl and ratchetmechanism comprises a bluff bar movable endwise by said female memberbetween bluffing and inoperative positions.

4. The apparatus as described in claim 1, wherein said driving cam has aplurality of crests for producing a plurality of oscillations of theoscillatable device during each revolution of the cam.

1. A ribbon feed and reversing mechanism for a traversing carriagetypewriter, comprising: a. two ribbon spools for carrying a ribbon, eachspool being carried by a rotatable mounting; b. driving means coupled toand driven from said carriage, and having a driving cam; c. a pawl andratchet mechanism connected to each said spool mounting, for drivingsaid spools; d. an oscillatable device, for operating said pawl andratchet mechanisms, connected to said pawl and ratchet mechanismsthrough two respective pawl bars, said device driven by said drivingcam; e. said device being rotatable into alternative rotationalpositions, such that said driving cam oscillates said device when in anyone of its alternative positions; f. detent means engaging said devicefor normally holding said device in any one said alternative positionwhile said device is being oscillated, said detent means being yieldablewhen said device is prevented from being oscillated to permit saiddevice to rotate from one alternative position to another; and g.bluffing means connected to and driven by said device for holding saidpawl and ratchet mechanisms in alternate nonoperative and operativepositions respectively, such that upon either spool encountering apredetermined resistance to rotation, said device is rotated to a nextof said alternative positions, the ribbon feed reversing as said deviceis rotated to each such position.
 2. The apparatus as described in claim1, wherein said bluffing means comprises a bluff-operating eccentricdevice rotationally movable with the oscillatable device betweenalternative positions for the alternative bluffing of the pawl andratchet mechanisms, a female member encircling said eccentric device anddisplaceable thereby to alternative positions, and bluffing connectionsextending from said female member to each pawl and ratchet mechanism,whereby one of said mechanisms is nonoperative and the other operativeaccording to the position of the female member.
 3. The apparatus asdescRibed in claim 2, wherein said bluffing connection extending fromsaid female member to each pawl and ratchet mechanism comprises a bluffbar movable endwise by said female member between bluffing andinoperative positions.
 4. The apparatus as described in claim 1, whereinsaid driving cam has a plurality of crests for producing a plurality ofoscillations of the oscillatable device during each revolution of thecam.